Indonesia's tourist island of Lombok is battling malaria, authorities said on Saturday, declaring a health emergency after a series of earthquakes in July and August forced hundreds of thousands to flee their homes.

The quakes and aftershocks that killed nearly 500 people are estimated to have caused damages of 5 trillion rupiah ($337.84 million) to hospitals and public infrastructure, among other buildings, on the island's northern coast.

Lombok is less developed than its neighbouring island of Bali, which is Indonesia's top tourist destination.

After the quake, aid groups said many of the hundreds of thousands left homeless were camping in open fields, refusing to seek shelter indoors as tremors continued.

Women and children are among the 128 people found to have been infected with malaria, Rahman Sahnan Putra, the chief of the West Lombok Health Agency, told Reuters by telephone.

‘It's an extraordinary occurrence of malaria,’ Putra said, confirming that an emergency had been declared.

The local government was seeking 3.4 billion rupiah ($230,000) from the central and regional governments to help fund mosquito nets, test kits and the emergency response effort, he added.

Although malaria is endemic in West Lombok, recent tests revealed a spurt in infections, another regional official said.

‘There was a mass blood survey and the entire community was checked,’ said Marjito, the chief of the health agency of West Nusatenggara, the province that is home to Lombok.

The incident was being treated as a ‘standard outbreak’, Marjito said, adding that those testing positive for the disease are treated, counselled and their surroundings sprayed with disinfectant.

Many of those infected had been living in tents after the quakes and did not get proper rest, making them more vulnerable, he added.

‘When people with malaria are weak, that's when issues arise,’ Marjito said, adding that authorities were mapping areas where malaria is endemic and planned to distribute thousands of mosquito nets as a preventive measure.

However, officials fear efforts to rein in the disease will be complicated by the arrival of the rainy season next month, as malaria-carrying mosquitoes breed in pools of stagnant water.

Assistance from the central government includes training for health officials in the use of microscopes to boost disease tracking, which had been disrupted by the disaster, said health ministry official Anung Sugihantono.

‘When they started carrying out observations properly, they found more cases, and because of this, that area has declared a state of emergency,’ he added.